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Related Concept Videos

Electrocardiogram01:29

Electrocardiogram

An electrocardiogram (ECG or EKG) is a critical diagnostic tool that records the electrical signals produced by the heart during each heartbeat. This recording is achieved through electrodes placed strategically on the arms, legs, and chest. The electrocardiograph amplifies these signals and produces 12 distinct tracings, offering a comprehensive understanding of the heart's electrical activity.
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and the T...
Correlation between ECG and Cardiac Cycle01:25

Correlation between ECG and Cardiac Cycle

The electrical signals recorded on an electrocardiogram (ECG) occur before the mechanical processes of contraction and relaxation during the cardiac cycle.
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
Cardiac Action Potential01:30

Cardiac Action Potential

Cardiac action potentials are essential for proper heart function, enabling the rhythmic contractions needed for adequate blood circulation. Nodal cells and Purkinje fibers, specialized for electrical conduction, generate these action potentials.
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
Acute Coronary Syndrome I: Introduction01:30

Acute Coronary Syndrome I: Introduction

Acute Coronary Syndrome (ACS) encompasses a spectrum of heart conditions caused by sudden obstruction of coronary arteries, typically resulting from the rupture of an atherosclerotic plaque and subsequent thrombus (blood clot) formation. This obstruction can lead to partial or complete blockage of blood flow, causing varying degrees of myocardial ischemia or infarction.ACS includes the following clinical entities:Unstable Angina (UA)Non-ST-Elevation Myocardial Infarction (NSTEMI)ST-Elevation...
Acute Coronary Syndrome II: Pathophysiology and Clinical Manifestations01:19

Acute Coronary Syndrome II: Pathophysiology and Clinical Manifestations

The pathophysiology of Acute Coronary Syndrome [ACD] involves several key processes:The main underlying cause of ACD is atherosclerosis, a chronic inflammatory disease characterized by the buildup of lipid-laden plaques within the coronary arteries.As the atherosclerotic plaque grows in the coronary artery, it may become unstable due to the formation of a lipid-rich core and a thin fibrous cap. Inflammatory cells within the plaque, such as macrophages, secrete enzymes that degrade the...
Acute Coronary Syndrome III: Diagnostic Studies01:30

Acute Coronary Syndrome III: Diagnostic Studies

Diagnosing acute coronary syndrome or ACS begins with a thorough patient history. Notable symptoms include central, crushing chest pain radiating to the left arm, neck, jaw, or back, along with shortness of breath, sweating (diaphoresis), nausea, vomiting, dizziness, and palpitations.It is crucial to note any history of cardiac illnesses and assess risk factors, including age, gender, smoking, hypertension, diabetes, hyperlipidemia, and a sedentary lifestyle.During physical examination, vital...

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Related Experiment Video

Updated: Jul 20, 2026

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis
18:11

A Research Method For Detecting Transient Myocardial Ischemia In Patients With Suspected Acute Coronary Syndrome Using Continuous ST-segment Analysis

Published on: December 28, 2012

Reversible QRS changes during acute myocardial ischemia

B Surawicz1

  • 1Krannert Institute of Cardiology, Indiana University School of Medicine, Indianapolis, USA.

Journal of Electrocardiology
|July 31, 1998
PubMed
Summary

Reversible QRS complex changes during acute myocardial infarction (AMI) are common and linked to ST-segment shifts. These QRS alterations, often affecting the terminal portion, indicate intraventricular conduction disturbances during ischemia.

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Area of Science:

  • Cardiology
  • Electrocardiography
  • Medical Diagnostics

Background:

  • Reversible QRS complex changes during acute myocardial infarction (AMI) are infrequently reported.
  • Systematic analysis of these electrocardiographic findings in a large patient cohort is lacking.

Purpose of the Study:

  • To systematically analyze reversible QRS complex changes in patients with acute myocardial infarction.
  • To characterize the specific types and prevalence of QRS alterations during AMI.

Main Methods:

  • Retrospective analysis of electrocardiograms from 29 patients with documented AMI and reversible QRS changes.
  • Detailed measurement of ST-segment deviation, QRS complex morphology, duration, and U wave amplitude.

Main Results:

  • Reversible QRS changes were observed in all 29 patients, with terminal QRS portion changes occurring in 100% and initial QRS portion changes in 79%.
  • Specific changes included increased S amplitude (62%), increased R amplitude (31%), and QS to qRS/qR transformation (21%).
  • Increased QRS duration was noted in 4 patients.

Conclusions:

  • Reversible QRS changes are a frequent finding during AMI, not just isolated occurrences.
  • These changes are attributed to passive pull from ST-segment shifts and associated intraventricular conduction disturbances.